Wireless ECG Devices Critical for ER Treating MI

May 21, 2008

May 21, 2008 - Paramedics equipped with pre-hospital ECG devices that wirelessly transmit critical information to emergency rooms while in route to the hospital, can reduce the time it takes to diagnose and treat patients by more than 30 percent, according to a study released at the Heart Rhythm Society's 29th Annual Scientific Sessions.

The study is the first to prospectively evaluate hospital time to treatment and outcomes in individuals randomized to receive a pre-hospital ECG versus the usual method of obtaining an ECG after hospital arrival.

An ECG is the primary tool used to diagnose and understand the severity of a myocardial infarction, or heart attack. The earlier a physician receives an ECG reading, the faster a patient can receive proper care or treatment. Beginning in 2003, all paramedic vehicles in Santa Cruz County, California, were equipped with special ECG devices, marking the launch of the Synthesized Twelve-lead ST Monitoring & Real-time Tele-electrocardiography (ST SMART) Study. These modified machines wirelessly transmit an ECG reading to the hospital through mobile phone technology, while continuously monitoring the patient's status and re-transmitting information to the hospital if changes are detected.

The ST SMART study measured two critical windows of time that directly link to survival and long-term well-being of a heart attack patient. Results showed that pre-hospital ECG transmissions shortened both the time to diagnosis, the time it took to receive the first ECG after the patient dialed 9-1-1, and door to balloon time, the time it took to receive treatment once a patient arrived at the hospital.

"The earlier you can treat heart attack patients, the lower the risk of permanent heart muscle damage, which is why reducing door to balloon time is so important," stated the study's lead author Barbara Drew, Ph.D., from the University of California, San Francisco. "By utilizing mobile phone/ECG technology, physicians are able to diagnose patients faster and mobilize resources in anticipation of a patient's arrival, rather than reacting once the patient is already in the door."

Patients randomized to the experimental group with pre-hospital ECG cell phone transmission had an initial ECG reading 59 minutes earlier than patients randomized to the control group with their first ECG reading at the hospital. This advanced ECG information from the field allowed physicians to diagnose and understand the severity of the heart attack much earlier, and prepare for treatment before the patient arrived. In addition, patients who received a pre-hospital ECG had an average door to balloon time of 79 minutes, 37 minutes faster than those who did not receive a pre-hospital ECG. To date, more than 730 patients have been enrolled in the ST SMART study.